Incidentally, it's mostly (post #174301, reply #5 of 10)

The original comes with two clamps that fit on the underside and slide in the tracks there, allowing it to be clamped to plywood with no "overhead" obstructions. Then you can run your saw along it with the motor overhanging the straightedge.

To deal with its flex in the joint, I'd use a strip of 1/2" plywood about 2" wide. Set the guide straight using another straightedge across the joint, then "buck" the joint by setting the plywood strip on the non-cutting side and clamping it. Unless one was close to the edge of the sheet, the clamp would be far enough back to not interfere with the motor.

If the joining mechanism had been better (and the clamps not so cheaply made) it would have been a pretty good tool. As it was, it was just tolerable -- better than nothing but a lot of trouble to use.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed. --Herman Melville

I use a shoot board for (post #174301, reply #7 of 10)

I use a shoot board for shorter cuts, but an 8-foot one is kinda awkward. I don't do much plywood chopping anymore, though, so I get along with the old STRATE-CUT when I need to do it.

And if the guide you're talking about is a standard rip gauge, the problem with those is that they can only cut as straight as the edge of the sheet, and quite often plywood sheet edges are not that straight (or square).

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed. --Herman Melville